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Big solar blowouts hold a clue to space weather

Last Updated on Monday, 23 June 2014 16:17

Published on Friday, 20 June 2014 14:05

Solar jets are ejections from the surface of the Sun, where 1-10 tonnes of hot material are expelled at speeds of up to 1000 kilometres per second. Using space based observatories like Hinode and STEREO, solar physicists have recently discovered a new type of jet known as 'blowout' jets, which seem to be like the Coronal Mass Ejections (CMEs) that can disrupt the magnetic field of the Earth, but on a much smaller scale.

A montage of images showing how the simulation closely matches observed events on the Sun. On the left are two images of the blowout jet eruption of 20 September 2008 observed using the Hinode observatory, showing how it changed over a period of five minutes. On the right are two frames from Eon Jui Lee’s simulation of a blowout jet eruption. Credit: Hinode / Eon Jui Lee / University of St AndrewsNow a St Andrews scientist, Dr Eon Jui Lee, has created a 3D model of these events for the first time, with compelling computer-generated simulations that match the jets' appearance from space. He will present his work at the National Astronomy Meeting (NAM 2014) in Portsmouth from 23-26 June.

The most common class of 'hot' solar jets are the 'standard' X-ray jets, which are believed to be formed by 'magnetic reconnection' i.e. when magnetic field lines of opposite direction ('north' and 'south') come into contact. Blowout jets are different and seem to be triggered by the eruption of the magnetic field at the base of the jet, which carries a twisted filament of material. At a temperature of 10,000 – 100,000 degrees Celsius, this is much cooler than the outer atmosphere of the Sun, where temperatures are typically between 1 and 2 million degrees.

On the Sun material is found in the form of plasma, a gaseous state where some electrons are stripped away from normally neutral atoms. In blowout jets, the eruption of relatively cool plasma leads to magnetic reconnection too and this in turn drives the eruption of hot plasma, so that both hot and cold material are carried into space. This makes them like miniature CMEs and suggests that a similar mechanism is at work.

Dr Lee's model shows the change from standard to blowout jets and frames from the simulation show a close fit between his work and pictures from the Hinode satellite. The model suggests that the twisted magnetic fields in standard jets become helical and drive the blowouts. Waves in the jet then transport material and energy into the outer atmosphere of the Sun and the wider Solar System.

He comments: "Solar physicists work hard to understand activity on the surface and in the atmosphere of the Sun. To see my simulations match real observations so well is wonderful. I hope that this work will help my peers working on space weather better understand and perhaps get more warning of events that might disrupt life on Earth."

https://www.ras.org.uk/images/stories/NAM/2014/Eon_figure_1.jpgA montage of images showing how the simulation closely matches observed events on the Sun. On the left are two images of the blowout jet eruption of 20 September 2008 observed using the Hinode observatory, showing how it changed over a period of five minutes. On the right are two frames from Eon Jui Lee's simulation of a blowout jet eruption. Credit: Hinode / Eon Jui Lee / University of St Andrews

https://www.ras.org.uk/images/stories/NAM/2014/Eon_movie_rho_bw.mp4A black and white movie made using frames from Eon Jui Lee's simulation, showing how a blowout jet erupts over a period of seven hours. The material in the jet quickly rises more than 60,000 kilometres above the surface of the Sun (at bottom) into the corona. Credit: Eon Jui Lee / University of St Andrews

https://www.ras.org.uk/images/stories/NAM/2014/Eon_movie_rho_colour.mp4A colour movie made using frames from Eon Jui Lee's simulation, showing how a blowout jet erupts over a period of seven hours. The material in the jet quickly rises more than 60,000 kilometres above the surface of the Sun (at bottom) into the corona. Credit: Eon Jui Lee / University of St Andrews

Further information

Dr Lee developed his model in collaboration with Dr Vasilis Archontis and Prof Alan Hood, also of the University of St Andrews.

Notes for editors

The RAS National Astronomy Meeting (NAM 2014) will bring together more than 600 astronomers, space scientists and solar physicists for a conference running from 23 to 26 June in Portsmouth. NAM 2014, the largest regular professional astronomy event in the UK, will be held in conjunction with the UK Solar Physics (UKSP), Magnetosphere Ionosphere Solar-Terrestrial physics (MIST) and UK Cosmology (UKCosmo) meetings. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Portsmouth. Meeting arrangements and a full and up to date schedule of the scientific programme can be found on the official website and via Twitter

The University of Portsmouth is a top-ranking university in a student-friendly waterfront city. It's in the top 50 universities in the UK, in The Guardian University Guide League Table 2014 and is ranked in the top 400 universities in the world, in the most recent Times Higher Education World University Rankings 2013. Research at the University of Portsmouth is varied and wide ranging, from pure science – such as the evolution of galaxies and the study of stem cells – to the most technologically applied subjects – such as computer games design. Our researchers collaborate with colleagues worldwide, and with the public, to develop new insights and make a difference to people's lives. Follow the University of Portsmouth on Twitter.

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others. Follow the RAS on Twitter.

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